TGen News

PHOENIX, AZ – A study led by researchers from TGen, part of City of Hope, and Arizona State University shows that pre-clinical models exposed to the herbicide glyphosate develop brain pathologies associated with neurodegenerative disease. The findings suggest the brain may be much more susceptible to the damaging effects of the herbicide than previously thought. Glyphosate, the active ingredient in Roundup, is one of the most pervasive herbicides used in the U.S. and worldwide.

The research, published today in the Journal of Neuroinflammation, identifies an association between glyphosate exposure and symptoms of neuroinflammation, as well as accelerated Alzheimer’s disease-like pathology. This study tracks both the presence and impact of glyphosate’s byproducts in the brain long after exposure ends, showing an array of persistent, damaging effects on brain health.

“Herbicides are used heavily and ubiquitously around the world,” said Patrick Pirrotte, Ph.D., associate professor in TGen’s Early Detection and Prevention Division, director of the Integrated Mass Spectrometry Shared Resource at TGen and City of Hope, and senior author of the paper. “These findings highlight that many chemicals we regularly encounter, previously considered safe, may pose potential health risks. However, further research is needed to fully assess the public health impact and identify safer alternatives.”

The glyphosate exposure also resulted in premature death and anxiety-like behaviors. The scientists discovered that these symptoms persisted even after they discontinued exposure for a 6-month recovery period. The study also revealed an accumulation of aminomethylphosphonic acid —a byproduct of glyphosate — in brain tissue, raising serious concerns about the chemical’s safety for human populations.  

“Our work contributes to the growing literature highlighting the brain’s vulnerability to glyphosate,” said Ramon Velazquez, Ph.D., assistant professor at the ASU-Banner Neurodegenerative Disease Research Center and one of the paper’s senior authors. “Given the increasing incidence of cognitive decline in the aging population, particularly in rural communities where exposure to glyphosate is more common due to large scale farming, there is an urgent need for more basic research on the effects of this herbicide.” 

The findings build on earlier work by the researchers that demonstrates a link between glyphosate exposure and a heightened risk for neurodegenerative illnesses including Alzheimer’s disease. 

The previous study showed that glyphosate crosses the blood-brain barrier, a protective layer that typically prevents potentially harmful substances from entering the brain. Once glyphosate crosses this barrier, it can interact with brain tissue and appears to contribute to neuroinflammation and other harmful effects on neural function. 

“My hope is that our work drives further investigation into the effects of glyphosate exposure, which may lead to a reexamination of its long-term safety and perhaps spark discussion about other prevalent toxins in our environment that may affect the brain,” said Samantha Bartholomew, a graduate research assistant with the ASU-Banner Neurodegenerative Disease Research Center and the paper’s first author.

The current study explored the idea that glyphosate exposure acts as an accelerant for Alzheimer’s disease pathology, extending the earlier findings. The researchers hypothesized that glyphosate exposure would induce neuroinflammation in controls and worsen neuroinflammation in Alzheimer’s models, causing elevated Amyloid-β and tau pathology, and worsening spatial cognition after recovery. Amyloid-β and tau are key proteins associated with brain tissue plagues and tangles within the cell bodies of neurons, the classic diagnostic markers of Alzheimer’s disease. 

The 13-week experiment, followed by a 6-month recovery period, tested glyphosate exposure in both normal and transgenic preclinical models with Alzheimer’s-like symptoms. Glyphosate exposure caused early death, increased anxiety, and impaired learning. Levels of Alzheimer’s-linked proteins (Amyloid-β 42 and phosphorylated tau) were higher in the brains. Inflammatory markers also increased in the brain and blood, persisting even after recovery. The study tested both high and low doses of glyphosate. Although the lower dose was below the EPA’s safety limit, it still caused brain damage, suggesting common glyphosate exposure could harm neurological health.

The preliminary data highlight a significant health concern for human populations. The researchers stress the need for continued vigilance and intensified surveillance of glyphosate’s neurological and other long-term negative health effects. 

The National Institutes on Aging, National Cancer Institute of the National Institutes of Health, and ASU Biodesign Institute funded this study.

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